CARBOHYDRATE METABOLISM AND GROWTH JX EDIBLE CANNA 
ent at first, but increases in diameter, assuming a tapering shape, as 
the quantity of food received increases. The surface type, which 
has two or more stems on which to draw, starts with a large attach- 
ment to the parent and develops an oval shape. 
Buds are produced in the axils of the scales of the rootstock. They 
are sometimes produced in profusion on the cylindrical type of root- 
stock, but most of 
them remain dormant. 
Ordinarily three buds 
develop on rootstocks 
of the intermediate 
type, being attached at 
intervals from near the 
base to the apical part 
of the mature root- 
stock. Usually only 
two vigorous buds 
grow on rootstocks of 
the surface or oval 
type, and they are at- 
tached near the apex. 
A number of other 
buds, termed "top 
buds," which are very 
small and dormant, 
grow at the very short 
nodes near the extreme 
apex of the rootstock. 
(Fig. 10.) Normally, 
these do not develop, 
although some of them 
may grow when the 
rootstock is used for 
seed. 
The vigor of the de- 
veloping bud seems to 
depend upon the age of 
the parent rootstock. 
A bud has maximum 
vigor if it starts to grow 
while the parent is 
young and rapidly de- 
veloping in the region 
of bud attachment. 
Growth is stunted, 
however, and the size 
of the rootstock ulti- 
mately greatly de- 
ceases, \i bud development is retarded until the parent is old (fig. 8) ; 
hence, the edible canna requires uniform growing conditions to make 
the best growth. 
Fields of canna failing to send out much new growth under adverse 
conditions may produce new stems in profusion with the return of 
Fig. 2.— Longitudinal section of an intermediate type of rootstock. 
A is the first node of the stem; B is the apex of the rootstock. 
The characteristic parallelism of the vascular bundles in the stem 
differentiates it from the rootstock proper 
